Connector for uniting coaxial cables



Sept. 3, 1957 w. w. LEEPER 2,805,399

CONNECTOR FOR UNITING COAXIAL CABLES Filed 001:. 4. 1955 MUN jam

INVENTOR 33 I? /6 William WLc-e er ATTORNEY United States Patent CONNECTOR FOR UNITING COAXIAL CABLES William W. Leeper, Worthington, Ohio Application October 4, 1955, Serial No. 538,400

Claims. (Cl. 333-6) This invention relates to connectors or couplings of the type employed in mechanically and electrically joining the sheathing encased, concentrically arranged, inner and outer conductors of a main unbroken coaxial cable at positions intermediate thereof with corresponding conductors of a branch or tap cable.

Such connectors or couplings, as heretofore constructed, have proved to be unsatisfactory and inadequate in meeting certain practical conditions incident to the usage thereof. Among these conditions, difficulty is encountered in maintaining efiective electrical contact at all times between adjoining portions of the united inner conductors of such cables. This is attributable quite often to the fact that the dielectric sheathing, employed in encasing the inner and outer conductors of such a cable, tends in practice to flow or shift, as in its response to unusual thermal conditions, or to gravitational effects produced as a result of the operating positions occupied by such cables when installed. As a result of such sheathing flow, the inner axially disposed and longitudinally extending conductor of such a cable is displaced laterally with respect to the true axial center of the cable body normally occupied thereby. Such displacement causes the conductor-engaging ends of associated pins or stems, arranged within the bodies of such connectors, to lose contact with the outer surfaces of inner conductors with which they are required to be in good electrical contact, and, therefore, operating circuits passing through the same are broken, or their operating characteristics rendered unsatisfactory.

Again, such connectors or couplings, as heretofore constructed, have included threaded joints and other interfaces through which water seepage readily takes place when the connectors are arranged in positions of exposure to the elements, as they most often are. Such water or moisture seepage interferes with the insulating properties of the connector or coupling and is a source of trouble in the proper functioning of television and other electronic apparatus to which the branch conductors most commonly lead.

Further, such connectors or couplings are formed so that current flow attenuating or modifying capacitative and/or resistance units are included in bridging devices conductively uniting the central or axial conductors of a pair of connector-joined coaxial cables. As presently formed, such connectors have the capacitor or resistor units or devices substantially permanently incorporated in their structure. It is often desirable in obtaining required potentials to replace a capacitor by a resistor or to use a capacitor in series association with a resistor so that any desired proportion of capacitance to leakage resistance may be obtained. Therefore, when such capacitor or resistor units are unremovably incorporated in the physical structure of such connectors or couplings expense and difiiculty are often experienced in obtaining unit substitutions.

With these and other objections in view, the present invention has for one of its general objects to provide a coupling or connector of this character, and for the uses and purposes set forth, wherein improved means are provided for maintaining at all times efiective electrical and physical contact between internally disposed conductor pins or stems of the connector and the inner axial conductor of an associated cable, such contact being maintained even though the inner conductor shifts in position relative to the true center of the cable in which it is arranged as a result of sheathing flow or displacement.

Another object is to provide a connector of this character with improved gasket means for positively excluding or sealing off the seepage of water or moisture, preventing the same from entering internally disposed conductor chambers or passages of the connector.

A further object is to provide improved means for clamping the terminating end portion of the outer conductor of the branch cable to the conducting body of the connector through a detachable coupling sleeve threadedly mounted on the branch cable-receiving end of the connector body, the end of the conductor being disposed between conical clamping surfaces forming a part of the sleeve and connector body and in a manner providing for a secure mechanical and electrical union of the conductor with said surfaces.

A still further object is to provide a connector of this character wherein the terminating end of the inner conductor of the branch or tap cable is mechanically joined in current-transmitting relationship with the corresponding conductor of an associated main cable in a manner avoiding the use of soldered connections.

Still another object is to provide a tap connector for coaxial cables which includes novel features of construction whereby the connector comprises an improvement generally in the class of devices to which it relates.

Other objects, advantages and novel features of construction and operation will be in part obvious and in part pointed out in the following description and the annexed claims.

In the accompanying drawings, which form a part of this specification and wherein similar characters of reference denote like and corresponding parts throughout the several views thereof:

Fig. 1 is a view in front elevation of a connector or coupler formed in accordance with the present invention "and used for uniting branch coaxial cables at desired positions in the length of a main or trunk coaxial cable;

Fig. 2 is a vertical longitudinal sectional view taken through the connector;

Fig. 3 is a fragmentary vertical transverse sectional view taken on the line 3-3 of Fig. 2 and showing the same provided with a single capacitor unit;

Fig. 4 is 'a detail horizontal sectional view taken on the line 4-4 of Fig. 2;

Fig. 5 is a fragmentary side elevational view of a coaxial cable to which the connector of the present invention is applicable;

Fig. 6 is a detail perspective view of the branch cableguiding and clamping core element of the connector;

Fig. 7 is an enlarged, fragmentary, vertical, transverse sectional View, disclosing the construction of the conductor-contacting end of the spring-pressed conductor stern employed in providing current flow between the inner conductors of connector-joined branch and main cables;

Fig. 8 is a vertical transverse sectional view, corresponding to Fig. 3 and disclosing the same provided with removable capacitor and resistor units in series relation;

Fig. 9 is a vertical sectional view disclosing a modified form of the invention wherein the inner conductors of the cable are mechanically joined without solder connection.

Referring more particularly to the drawings, my improved tap connector or coupler C is shown as comprising a metallic body composed primarily of a base section 1 and a separable cap section 2. These sections are formed with substantially flat abutting surfaces provided with longitudinally extending vertically registering grooves 3, adapted for clamping reception of a main or primary cable 4. As shown in Fig. 2, the connector body in this instance is held in clamped engagement with the cable 4 by means of headed screws 5. These screws have their shanks loosely received in openings 6 formed in the cap section 2 and threaded into vertically aligned openings 1' formed in the base section 1. When these screws are tightened the base and cap sections are drawn together by the action of the screws and held so that the wall surfaces of the grooves are maintained in firm, frictional clampingengagement with the cable 4, whereby to main:

tain the connector in secured union with said cable and to enable the connector to be disposed at any desired position thereon'throughout its available length.

In this instance, the cap section 2, as shown in Pig. 2, is formed with a threaded opening for the reception of a piercing screw 8 having a conically tapered inner end. When the connector is applied on a main cable, the screw 8 is rotated,.causing its tapered or pointed inner end to penetrate the insulating sheathing 9 of the cable 4 and press firmly against and into the interwoven wire strands of a conventional outer tubular return or ground conductor 10, the latter being embedded in the sheathing 9 and extending longitudinally of the cable 4 in concentric relation with its axial center. By this construction, or its equivalent, the metallic body of the connector C is electrically connected with the ground conductor 10.

As usual, the cable 4 includes an inner, centrally disposed, longitudinally extending, energy-distributing, core conductor 11, the latter being disposed in the axial center of the cable and embedded in the sheathing 9, so that the associated ground conductor 10 will be electrically spaced from the core conductor and disposed in concentric coextensive relation therewith, forming a conducting instrumentality known as a coaxial cable. The connector C is utilized primarily as an improved and convenient device for uniting the conductors of one or more tap, leadin or branch cables 12 with those of the main cable 4 at any suitable position in the length of said main cable.

Each tap or branch cable is of the same construction as the associated main cable, including a central energysupplying, axially disposed conductor 13, an insulating body or sheathing 14 and an outer tubular ground conductor 15, the latter being disposed concentrically about the center conductor 13. Each tap cable extends from the main cable 4 to an associated energy-utilizing appliance, not shown, such as a television receiver.

In uniting the conductors of the main and tap cables, the base section 1 of the connector C is formed with a lower end 16 of reduced diameter as compared with the upper body regions of the base section. The end 16 is exteriorly threaded for the reception of the internally threaded upper end of a coupling sleeve or ferrule 17. The latter has its lower end formed with an inturned flange 18, which is formed within the sleeve or ferrule with a conically tapered seat 19 which at its lower or outer end terminates in an opening 20 of reduced diameter. Through this opening there is passed the terminating end region of the branch cable 12.

The end of the cable 12, which is to be inserted in the coupling sleeve 17, is first prepared after the manner disclosed in Figs. 2 and 5, which enables the sheathing 14 thereof disposed about the outer, tubular, braided or interwoven wire conductor 15, and the conductor itself, to engage the conical seat 19, whereby to electrically join. the conductor 15 with the body of the connector.

This operation is rendered positive by the inclusion of the rigid core element shown at a, preferably of insulating composition. This element at its inner or upper end, as the construction is viewed in Fig. 2, is formed with a conical enlargement 21 which is inwardly shouldered at 22 to receive a depending peripheral flange 23 formed on a compressible gasket disk 24, the latter being preferably composed of rubber or one of the plastics, such as polyethylene or other equivalent material, said disk being interposed between the lower end 16 of the body 1 and the upper surfaces of the core element 29a. It will be seen that when the coupling sleeve 17 is tightened on the threads of the reduced lower end 16 of the body section 1 of the connector, and with the conical enlargement 21 entering the open upper end of the sheathing 14, said sheathing and the portions of the conductor 15 projecting beyond the same, will be clamped between the conical surfaces, with the exposed outer or upper end of the conductor 15 in direct and firm contact with the inner surfaces of the sleeve 17. At the same time, the disk 24 is compressed, sealing ofi the open lower or outer end of the body section 1. V V

The outer or lower portion of the core element provides a reduced tubular portion 22a which extends through the opening 20 in the lower or outer end of the sleeve 17 and terminates exteriorly thereof in a frusto-conical tip 23a. A resilient clamping collar 24a surrounds the cable sheathing 14 between the lower end of the sleeve 17 and the core tip 23 to securely hold the branch cable 12 against displacement. By the use of the collar 24a, applied as shown, the cable sheathing is gripped in a manner efi'ectively sealing the sleeve opening 20 against moisture admittance, so that dry contact is maintained between the conductor 15 and the sleeve walls.

The disk 24 is provided with an axial opening for receiving the annularly flanged lower or outer end of a metallic thimble 25. Through this thimble there is extended the unsheathed upper or inner end of the central conductor 13 of the branch cable. The thimble projects into a chamber 26 formed longitudinally and axially in an insulating bushing 27, which, in turn, is positioned in an open-ended socket 28 formed in the body section 1 of the connector. At its upper or inner end the bushing is formed with an annular tapering shoulder 29 which terminates in a hollow, longitudinal projection 30, the

latte-r being positioned in an opening 31 formed in the upper or inner end of the body section 1 and, also, in a continuing opening 32 which is produced in the sheathing 9 of the main cable 4 as a preliminary step to the application of the connector.

Surrounding the thimble 25 is the lower or outer end of a coiled wire spring 33, the upper or inner end of the spring pressing against a socketed element 34 which receives the lower or outer terminal 35 of a removable attenuating unit 36 in the form of a capacitor or resistor. The unit is received in a reduced bore 37 formed as an axial continuation of the chamber 26. The upper terminal 38 of the capacitor unit engages the headed end of a conductor stem 39, which at its upper or inner end, as shown in Fig. 7, instead of being formed with a pointed conductor-penetrating end, as heretofore, is formed with an arcuately concaved surface 40 adapted for closefitting and interlocking contact with the inner conductor 11 of the main or trunk cable 4.

From the foregoing it will be evident that when the main and branch cables 4 and 12 are united by the connector, in the manner shown in Fig. 2, the spring 33 applies a force maintaining a good electrical contact between the spring 33, the seating element 34, the capacitor unit terminals 35 and 38, the stem 39 and the conductor 11. If the conductor 11 should through migration of the sheathing 9 become displaced from its normal position in the true axial center of the cable 4, the arcuately concaved surface 40 of the spring-pressed stem 39 will serve to cause the stem to retain its contacting engagement with the conductor 11, even though such displacement may be of an extreme character.

By removing the coupling sleeve 17 from the body 1 of the connector, the chamber 26 of the bushing 27 is rendered conveniently accessible, so that when conditions require it, the capacitor unit if defective, or if a different value is indicated, a new or different unit may be readily substituted. As shown, for example, in Fig. 8 a 10 M. M. F. capacitor is combined with a one-half watt 470 resistor unit. Such a resistor offers sufficient resistance so that some current leakage occurs, but not enough to overshadow the capacitive effect, whereby any desired proportion of capacitance to leakage resistance may be obtained. Such adaptation may be quickly and conveniently made and is in marked contrast with units permanently cemented or otherwise incorporated in such connectors.

While I have referred to the outer conductors 10 and of the main and branch cables as being the ground or return conductors and the central or core conductors 11 and 12 of said cables as forming the energy-advancing or antenna-united conductors, it will be understood that such nomenclature is employed for convenience and clarity in description and not by way of limitation, since said conductors may be employed in other capacities.

In Fig. 9, the thimble a is shown as having an enlarged internal passage 42 in which is positioned a tapering coil spring 43. This spring is designed to grip firmly the terminating end of the inner conductor 13 of the branch cable, whereby to unite the same electrically with the thimble without requiring soldered connections, as are usually required at 44 in the construction of Fig. 2.

Having thus described my invention in connection with one of its preferred embodiments, it will be appreciated that the features of my improved connector are subject to certain variation or modification without departing necessarily from the spirit and scope of the invention as defined by the following claims.

I claim:

1. A connector for mechanically and electrically joined main and branch coaxial cables, each of said cables being of the type including an insulating sheathing having deposited therein an axial longitudinally extending inner conductor and an outer concentrically disposed tubular conductor; said connector comprising: a member of conductive material composed of separable body and cap sections; threaded means uniting said sections in fixed clamping relation on a main cable passing between said sections; a sheathing-piercing contact device carried by one of said sections for electrically joining the same with the outer tubular conductor of said main cable; the body section of said connector being externally threaded at its outer end and formed with an internal longitudinally extending socket, the latter being open at its outer end and having its inner end formed with a conical seat, said socket beyond said seat terminating in an extension of reduced diameter and which is disposed in registry with a transverse opening in the sheathing of the main cable, said opening extending radially of the sheathing from its outer circumferential surface to the inner conductor contained therein; a bushing of insulating material positioned in said socket, said bushing having a shouldered inner end arranged for engagement with the conical seat of the socket, the inner end of said bushing terminating in a tubular extension occupying the transverse opening in the sheathing of said main cable; said bushing including an axially disposed chamber open at its outer end, the inner end of said chamber terminating in reduced passage establishing communication between said chamber and the transverse opening in said sheathing at the inner end of said tubular extension; a coupling sleeve internally threaded at one end for adjustable mounting on the external threads of said connector body, said sleeve including an internal bore formed at its outer end with a conical seat terminating in a'reduced opening through which passes a branch cable; a gasket mounted on said sleeve to seal against moisture entrance the open ends of said socket and chamber; and a rigid core member engaged with said gasket having an axial passage for the reception of the inner conductor of said branch cable, said core member being formed at its inner end with a conically tapered clamping head engaged with the conical seat of said sleeve for clamping the terminal portion of the outer conductor and surrounding sheathing of the branch cable between the adjacent conical surfaces of said head and seat.

2. A cable connector as defined in claim 1, and wherein the gasket carries a shouldered thimble receiving the inner conductor of the branch cable, said gasket having a recessed face in which a reduced and shouldered end of the head portion of said core member is received, said gasket having a fiat outer face disposed for sealing contact with the outer end edges of said connector body and bushing.

3. A connector for coaxial cables as defined in claim 1, including a current attenuating device positioned in the chamber of said bushing and projecting conductor terminals at its inner and outer ends, spring-pressed conductor means confined between said gasket and the outer terminal of said attenuating device; and a conductor stem disposed in the reduced extension of said bushing and having opposite ends electrically engaging respectively for engagement with the inner conductor of the main cable and said current attenuating device, the end of said stem engaging the main cable being formed with a hollow substantially concave seat receiving the inner conductor of the main cable.

4. A connector for mechanically and electrically joined main and branch coaxial cables of the type including insulated sheathings having deposited therein an axially extending inner conductor and an outer concentrically dis posed tubular conductor, said connector comprising a member of conductive material including separable body and cap sections; means uniting the body and cap sections of said member in fixed clamping relation upon a main cable positioned between said sections; a sheathingpiercing contacting device carried by and electrically connected with one of said sections for electrically joining said member with the outer tubular conductor of said main cable, the body section of said member being formed with an internal longitudinally extending socket open at the outer end thereof and having its inner end formed with a conical seat, said socket beyond said seat terminating in an extension passage of reduced diameter disposed in registry with a transverse opening formed in the sheathing of said main cable, said opening extending radially of the sheathing from its outer circumferential surface to the inner conductor contained therein; a bushing of electrical insulating material positioned in the socket of said body section and formed with a shouldered inner end arranged for engagement With the conical seat of said socket, the inner end of said bushing terminating in a tubular extension arranged to extend into the transverse opening formed in the sheathing of said main cable, said bushing being formed with an axially disposed chamber opening at the outer end thereof and terminating at its inner end in a reduced passage establishing communication between the chamber of said bushing and the transverse opening formed in said sheathing; a coupling sleeve detachably connected with the outer end portion of the body section of said member, said sleeve being formed with an internal bore terminating at the outer end of said sleeve in an annular inturned conical seat defining a relatively reduced opening for the reception of a branch cable; a metallic core member formed with an axial passage for the reception of the inner conductor of the branch cable, said core member being formed with a conically tapered clamping surface disposed in complemental clamping relation to the inturned flange of said sleeve, the clamping surface of said core member and the inturned flange of said sleeve being arranged to receive and clamp therebetween the terminal portion of the outer conductor and surrounding sheathing of the branch cable; an insulating gasket disposed between '7 said core member and the open outer ends of the body section of said member and said bushing and arranged to seal tr e latter against the entry of moisture; and electrical conductor means carried in said gasket and said bushing for establishing an electrical connection between the inner conductors of the main and branch cables.

5. A connector for mechanically and electrically joined main and branch coaxial cables of the type including an insulating sheathing having deposited therein an axially extending inner conductor and an outer concentrically disposed tubular conductor, said connector comprising relatively separable metallic body and cap members detachably clamped on the main cable with the principal axis of the body membr disposed substantially perpendicular to the main cable, said body member being formed with a socket extending axially thereth'rough; an axially chambered open-ended insulating bushing removably positioned in the socket of said body member; an annular gasket of compressible insulating material arranged to close the adjoining outer ends of the socket of said body member and the chamber of said bushing; a metallic coupling sleeve formed for detachable connection with the outer end of said body member 'and'having at the outer end thereof an inturned annular flange defining an opening of lesser diameter than said gasket, said lastnamed opening receiving therethrough the branch cable to be connected With the main cable; and a metallic core element electrically connected with the outer conductor of the branch cable and formed with a flat gasket engaging body serving to clamp said core element tightly against said gasket to force the latter into tight sealing engagement with the socket of said body member and the chamber of said bushing to maintain the latter against Water ingress.

References Cited in the file of this patent UNITED STATES PATENTS 112,798 Freeman Mar. 21, 1871 2,118,103 O'eding May 24, 1938 2,418,531 Tognola Apr. 8, 1947 2,422,982 Quackenbush June 24, 1947 2,429,654 Violette et al. Oct. 28, 1947 2,694,183 Edlen et a1 Nov. 9, 1954 OTHER REFERENCES Fletcher, R. C. Review of Scientific Instruments, Dec. 1949, page 864. 

